Yesterday, I noticed that the refrigerator portion of my unit was not cooling, but the freezer was like sub-zero.
I've seen this problem before: typically it means that somebody didn't close the door all the way, a lot of moisture got inside the unit, and the airflow from the freezer to the refrigerator got blocked by the resulting ice.
I unplugged the unit overnight, and I observed that there were no obstructions this morning, so I plugged the unit back in.
To my surprise, I am still observing a sub-zero freezer with a non-cool fridge.
I see that the compressor fan is running, the freezer fan is running, and there does not appear to be any obstruction in the duct at the bottom of the freezer that carries the cold air to the refrigerator. I also do not see any sort of additional fan that is being used to force the air into the fridge, so I do not see any other components that could possibly be causing this problem. Yet, even if I put my hand right next to the duct, I don't feel much cold air entering the fridge (and certainly not enough to keep anything cool).
And, yes, I've turned the refrigerator control to coldest, so that's not the problem.
This one is very confusing... any ideas?